1. Field of the Invention
The present invention relates to an air intake structure for a small watercraft. More particularly, the present invention relates to an air intake structure for a small watercraft in which the air intake efficiency is improved, and thus the power output of the engine may be improved.
2. Description of the Background Art
A number of different air intake structures for small watercraft have been known. An air intake structure for a small watercraft is disclosed in Japanese Patent Document JP-A-2000-335486. The air intake structure disclosed in this reference includes an air intake silencer in front of the engine, for introducing fresh air thereto. The air intake disclosed in the reference also includes a plurality of air ducts for communicating between the interior and the exterior of the watercraft body, wherein openings of the air ducts in the watercraft are disposed separately at the front and the back of the air intake silencer.
When providing a turbocharger on an engine for improving its output, generally, the turbocharger and air intake components for introducing fresh air thereto (air intake silencer or air cleaner case) are disposed adjacent to each other, in other words, are disposed together either at the front or the back of the engine. A connecting pipe can shorten the distance between the turbocharger and the air intake components.
Therefore, in the published art described above, the turbocharger is generally located on the side of the engine where the air intake silencer is located; that is, at the front of the engine.
Alternatively, when locating the turbocharger at the back of the engine, the air intake components are generally located at the back of the engine.
However, when a small watercraft is equipped with a turbocharger, improvement in the power output of the engine has been less than expected.
As a result of research, it was found that since there is not a large amount of space inside the small watercraft, high air temperatures tend to persist in the watercraft. In general, lower intake air temperatures generally correlate to higher engine power, since cooler air is denser.
The turbocharger itself is a heat source, and when the turbocharger and the air intake components are located close together, high temperature air around the turbocharger is easily introduced into the air intake, whereby air intake temperature increases, lowering the engine power output.
In the air intake structure for a small watercraft according to Japanese Patent Document JP-A-2000-335486, the openings of the air ducts in the watercraft are separately disposed at the front and rear of the air intake silencer. As a result, air is drawn into the air intake silencer through the opening of the air duct disposed at the front, and also through the opening of the air duct disposed at the rear. However, since the air intake silencer is located forward of the engine, air from the air ducts located at the rear is routed from the air intake silencer through the area surrounding the engine, which is a heat source.
Accordingly, since a large amount of high temperature air around the engine is drawn into the air intake silencer, there is a problem in that the air intake efficiency is lowered due to increase in intake temperature, and the output of the engine is also undesirably lowered.
Although the known devices have some utility for their intended purposes, a need still exists in the art for an improved air intake for use in a small watercraft. In particular, there is a need for an improved air intake structure for a small watercraft in which the air intake efficiency is improved, and thus the power output of the engine may be improved.